As catalysts for the process of hydrogenolysis use of N,N-dimethyl-3,5-ditert.butyl-4-hydroxybenzylamine is made of such known catalysts as Ni-Cu/Al.sub.2 O.sub.3, Pd/Al.sub.2 O.sub.3, Pt/Al.sub.2 O.sub.3, Pd/C, Ni deposited on kieselguhr, and a catalyst based on a nickel-aluminum alloy doped with titanium in an amount of from 1 to 8% by weight.
A nickel-aluminum alloy catalyst with a dope of titanium has proven to be the most proper among the prior art catalysts for the reaction of hydrogenolysis for a long run, and possesses sufficient selectivity. The desired product yield, upon performing the process with said catalyst, is as high as 98-99% by weight. However, the presence of 1-2% by weight of an impurity, i.e. stilbenequinone imparts to the desired product a yellow color which requires a double recrystallization, thereby the complicating process.
Furthermore, the catalyst is insufficiently active. Thus, at a temperature of 120.degree. C N,N-dimethyl-3,5-ditert.butyl-4-hydroxybenzylamine is completely converted within 3 hours.
For this reason, catalysts based on the alloy of NiAl.sub.3 with an additive of molybdenum and those with an additive of chromium (Ni 46-48% by weight, Cr 2-5% by weight, Al the balance) have been introduced in the art for the process of hydrogenolysis of N,N-dimethyl-3,5-ditert.butyl-4-hydroxybenzylamine.
With the use of said catalysts, the reaction duration at a temperature of 120.degree. C is 2 hours; productivity is increased by 30%, the content of stilbenequinone in the reaction mixture is reduced to 0.1-0.2% by weight; and the desired product acquires no yellow tint upon storage for one year. Output of the desired product is 67 ton/ton of the catalyst.
To eliminate the side reactions resulting in the formation of stilbenequinone, it is necessary to reduce the time of contact of N,N-dimethyl-3,5-ditert.butyl-4-hydroxybenzylamine and agidol with the catalyst; however, the catalyst activity cannot be increased by increasing the hydrogenolysis temperature, since this results in a noticeable resin-formation.